1. Field of the Invention
The present invention relates to a substrate of a touch panel, and more particularly to a substrate having wires mounted on a rough surface on a dielectric layer of the substrate so that the wires are uneasy to be fractured or come off.
2. Description of the Related Art
To keep abreast of advancement of technology, electronic equipment has an ever-demanding requirement concerning miniaturization, portability, operational simplicity and the like. As the touch technology gets rid off the use of a keyboard to fulfill the downsizing requirement of electronic products, touch panels have been vastly applied to electronic equipment such as personal digital assistants (PDA), mobile phones and the like, recently. The technologies of touch panels can be classified into capacitive type, resistive type, surface acoustic wave type, optical type and the like. Among them, the resistive touch panels are leading in terms of the global market share of touch panels, which is about 60% and more. The resistive touch panels are mainly applied to electronic products, such as self-service order system, PDA, electronic dictionary, mobile phone, inventory management machine, point-of-sale (POS) cash register, signature capture credit card processing POS terminal, medical surveillance system and the like. As the resistive touch panels are induced by pressure, touch media used to generate a touch signal are not restricted. The resistive touch panels can be operated by any one of a hand, a pencil, a credit card, a wood stick or the like or even by a hand wearing a glove. The resistive touch panels can be categorized into 8-wire, 7-wire, 6-wire, 5-wire, 4-wire resistive touch panels and the like.
Regularly, a touch panel has at least one substrate. Each one of the at least one substrate has an indium tin oxide (ITO) conductive layer, a wiring area and multiple wires. The ITO conductive layer is formed on the substrate. The wiring area is formed around three sides of a perimeter of the ITO conductive layer. The wires are printed on the wiring area and electrically connected to the ITO conductive layer. The wires are concentrated and connected to multiple leading lines. After the intelligent touch screen mobile phones, such as iPhone from Apple Inc., are released to the market, multi-touch operation can be achieved by capacitive touch panels. However, as the capacitive touch panels involve precise and sophisticated computation techniques, the production cost thereof is still high. In contrast, a resistive touch panel is advantageous in simple structure and lower cost. Therefore, multi-touch resistive touch panels are developed to emerge in the market.
To achieve a multi-point touch effect, a conventional resistive touch technology divides a conductive layer formed inside the touch panel into multiple blocks. Each block is electrically connected to the leading lines through an electrode and a wire. A user can simultaneously touch the blocks with fingers or tools, such as a stylus, to indirectly achieve a multi-touch operation effect generated by touching multiple points. An improved matrix touch panel based on the resistive touch technology can achieve the intended multi-touch effect by dividing the ITO conductive layer into multiple strip-like conductive layers. To maintain the accuracy of the touch panel and a multi-touch operation effect generated by touching multiple points, increasing the number of conductive layers is inevitably a trend to go in production. While more blocks are divided, the wires connected to the ITO layer also increase. To take operational requirement into account, the size of the ITO conductive layer must be maintained at a certain range. If the number of the wires increases and the wiring area is kept at a certain size for matching the size of the conductive layer, the width of the wires must be reduced so that the wires can be arranged on a limited space of the substrate.
If the wires are printed on the substrate, the widths of the wires are uneasy to be reduced. Uneven widths of the wires can lead to unstable or even increased resistance value of the wires. Additionally, the surface of the substrate is very smooth, and the wires are difficult to be firmly formed on the substrate. A contact area between a wire with reduced width and the substrate also decreases, thereby making the wires easily come off from the substrate and get fractured.